This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Cell membrane dynamic responses can be influenced by the onset and progression of human diseases. Fluctuations in the phospholipid bilayer and attached spectrin cytoskeleton are known to be altered by cytoskeletal defects, stress, and actin-spectrin dissociations arising from metabolic activity. Proteins transported from invading organisms, such as the malaria-inducing parasite P. falciparum, to specific binding sites in the spectrin cytoskeletal network induce significant alterations to RBC membrane dynamics and nanomechanical response. Using Diffraction Phase Microscopy, we investigate membrane fluctuations in human RBCs parasitized by P. falciparum over the full range of intra-erythrocyte stages.